/Engine/Source/Runtime/MeshConversion/Public/DynamicMeshToMeshDescription.h
Use the TMeshTangents to update the Tangent and BinormalSign attributes of the MeshDescription, assuming mesh topology has not changed. Does not modify any other attributes. NOTE: this ignores any tangent or bitangent overlays on the MeshIn, and instead uses the tangent and bitangent information stored in the TMeshTangents NOTE: assumes the order of triangles in the MeshIn correspond to the ordering you'd get by iterating over triangles, on MeshOut This matches conversion currently used in MeshDescriptionToDynamicMesh.cpp, but if that changes we will need to change this function to match!
void UpdateTangents ( const [FDynamicMesh3](API\Runtime\GeometryCore\DynamicMesh\FDynamicMesh3) * MeshIn, [FMeshDescription](API\Runtime\MeshDescription\FMeshDescription) & MeshOut, const [UE::Geometry::TMeshTangents](API\Runtime\GeometryCore\DynamicMesh\TMeshTangents)< double > * SrcTangents )